I've done a quick search through these forums but haven't really found anything conclusive yet. I've just finished a contract with O2 so I have kept my iPhone 4S and taken out a new Virgin sim only deal. However the signal in my house is non existent. My family members have Virgin and don't have a problem at all, and I was also using Virgin up to 5 years ago with no problems. There is no signal problem if I go into a different area.
I spoke to support who said to restore network settings (didn't make a difference), set carrier to auto (also no difference) and to manually set DNR settings. I have no idea what they are?? If that fails they say to post on these forums!
As I frequently work from home I cannot be without signal so I am tempted to cancel this contract and go back to O2 with my tail between my legs!
So sorry to here you are unable to get signal from your house. Looks like your have done a few diagnostics already which has not resolved the issue.
Please call our technical team on 789 (any Virgin Mobile Phone) or 150 (Virgin Land line) or 0845 6000 789 (from any other Landline) open between 8am-8pm Mon-Sun so we can look in to this further for you as it could be the sim card.